Thin film transistor array panel and method of manufacturing the same

ABSTRACT

A thin film transistor array panel according to an exemplary embodiment of the present invention includes: an insulating substrate; a polycrystal semiconductor layer formed on the insulating substrate; a buffer layer formed below the polycrystal semiconductor layer and containing fluorine; a gate electrode overlapping the polycrystal semiconductor layer; a source electrode and a drain electrode overlapping the polycrystal semiconductor layer and separated from each other; and a pixel electrode electrically connected to the drain electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent application Ser. No. 14/879,993 filed on Oct. 9, 2015, which claims priority to Korean Patent Application No. 10-2015-0000225 filed in the Korean Intellectual Property Office on Jan. 2, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Field

Embodiments of the present invention relate generally to flat panel displays. More specifically, embodiments of the present invention relate to thin film transistor array panels and their methods of manufacture.

(b) Description of the Related Art

A thin film transistor (TFT) has been used in various fields, for example as a switching and driving device in flat display devices such as liquid crystal displays (LCDs), organic light emitting diode displays (OLED Displays) and electrophoretic displays.

The TFT includes a gate electrode connected to a gate line transferring a scanning signal, a source electrode connected to a data line transferring a signal to be applied to a pixel electrode, a drain electrode facing the source electrode, and a semiconductor electrically connected to the source electrode and the drain electrode.

The semiconductor is an important factor in determining characteristics of the thin film transistor. Silicon (Si) is the most widely used semiconductor. Silicon is classified as an amorphous silicon or polysilicon depending on its crystal form, wherein amorphous silicon is relatively easily manufactured but has low charge mobility, while polysilicon has problems such as film burst in manufacturing.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY

Embodiments of the present invention provide a thin film transistor array panel and a method of manufacturing the same, having advantages of preventing polycrystal semiconductor layer film bursting and improved durability.

An exemplary embodiment of the present invention provides a thin film transistor array panel including: an insulating substrate; a polycrystal semiconductor layer formed on the insulating substrate; a buffer layer formed below the polycrystal semiconductor layer and containing fluorine; a gate electrode overlapping the polycrystal semiconductor layer; a source electrode and a drain electrode overlapping the polycrystal semiconductor layer and separated from each other; and a pixel electrode electrically connected to the drain electrode.

The buffer layer may comprise one or more hydrogen diffusion prevention layers each including the fluorine.

The one or more hydrogen diffusion prevention layers may each comprise a material of the buffer layer and the fluorine.

The buffer layer may include a SiNx layer and a SiOx layer stacked on the SiNx layer, and the one or more hydrogen diffusion prevention layers may be deposited at one or more of a middle of the SiNx layer, an interface between the SiNx layer and the SiOx layer, a middle of the SiOx layer, and above the SiOx layer.

The hydrogen diffusion prevention layer may each comprise SiOF or SiNF.

Another embodiment of the present invention provides a method of manufacturing a thin film transistor array panel, the method including: stacking a buffer layer containing fluorine on an insulating substrate; stacking an amorphous silicon (a-Si) layer on the buffer layer; performing a dehydrogenation process on the buffer layer and the amorphous silicon layer; crystallizing the amorphous silicon layer so as to form a polysilicon (poly-Si) layer; forming a polycrystal semiconductor layer by patterning the polysilicon layer; forming a gate electrode overlapping the polycrystal semiconductor layer; forming a source electrode and a drain electrode overlapping the polycrystal semiconductor layer and separated from each other; and forming a pixel electrode electrically connected to the drain electrode.

The stacking a buffer layer may further comprise forming one or more hydrogen diffusion prevention layers that include the fluorine.

The one or more hydrogen diffusion prevention layers may comprise a material of the buffer layer and may further comprise the fluorine.

The one or more hydrogen diffusion prevention layers may be formed by plasma treatment using a gas containing the fluorine.

The stacking a buffer layer may further comprise stacking a SiOx layer on a SiNx layer, and the forming one or more hydrogen diffusion prevention layers may be performed during a process of stacking the SiNx layer, after a process of stacking the SiNx layer, during a process of stacking the SiOx layer, and after a process of stacking the SiOx layer.

The one or more hydrogen diffusion prevention layers may comprise SiOF or SiNF.

The one or more hydrogen diffusion prevention layers may be formed by plasma treatment using a gas containing fluorine.

According to methods of manufacturing the thin film transistor array panel of the present invention, durability of the polycrystal semiconductor layer may be improved, and characteristics of the thin film transistor may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of a method of manufacturing a thin film transistor array panel according to an exemplary embodiment of the present invention.

FIG. 2 schematically shows a thin film transistor array panel according to an exemplary embodiment of the present invention.

FIG. 3 is a flow chart of a method of manufacturing a thin film transistor array panel according to an exemplary embodiment of the present invention.

FIG. 4 schematically shows a thin film transistor array panel according to an exemplary embodiment of the present invention.

FIGS. 5 to 8 sequentially show a method of manufacturing a polysilicon layer according to an exemplary embodiment of the present invention.

FIGS. 9a to 9c partially show modified exemplary embodiments according to different positions of a hydrogen diffusion prevention layer of the present invention.

FIG. 10a schematically shows an effect obtained by an exemplary embodiment of the present invention.

FIG. 10b schematically shows an effect obtained by a Comparative Example of the present invention.

FIG. 11 is a Table showing experimental results according to an exemplary embodiment of the present invention.

FIG. 12 is a Table showing experimental results according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention. However, the present invention is not limited to the exemplary embodiments which are described herein, and may be modified in various different ways.

Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In addition, in various exemplary embodiments, a first exemplary embodiment will be representatively described and therefore, only components other than those of the first exemplary embodiment will be described in other exemplary embodiments.

In addition, in the drawings, the size and thickness of each component shown in the drawings are optionally shown for convenience of explanation, for example, thickness is exaggerated for clearly expressing various layers and regions in the drawings, and therefore, the present invention is not necessarily limited to the shown exemplary embodiments in the drawings. Also, the drawings are not to scale.

All numerical values are approximate, and may vary. All examples of specific materials and compositions are to be taken as nonlimiting and exemplary only. Other suitable materials and compositions may be used instead.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on”, “above”, or “below” another element, it may be directly on the other layer or substrate or intervening elements may also be present. In addition, it will be understood that when an element such as a layer, film, region, or substrate is referred to as being “in the middle of” another element, the element may be disposed at the exact middle position in view of the distance and between the elements.

In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

Hereinafter, a thin film transistor array panel and a method of manufacturing the same according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a flow chart of a manufacturing method for a thin film transistor array panel according to an exemplary embodiment of the present invention, and FIG. 2 schematically shows a thin film transistor array panel according to an exemplary embodiment of the present invention.

First, referring to FIG. 2, the thin film transistor array panel according to an exemplary embodiment of the present invention may include an insulation substrate 100, a buffer layer 120 a containing fluorine, a polycrystal semiconductor layer 131, a gate electrode 150, a source electrode 170 s, a drain electrode 170 d, and a pixel electrode 190.

Referring to FIG. 2, the insulation substrate 100 may include the buffer layer 120 a containing fluorine, and the polycrystal semiconductor layer 131 on the buffer layer 120 a. A gate insulation layer 140 is disposed on the polycrystal semiconductor layer 131, the gate electrode 150 is disposed on the gate insulation layer 140, and an interlayer insulation layer 160 is disposed on the gate electrode 150. A first contact hole 161 a for connecting the source electrode 170 s with a source region 131 s of the polycrystal semiconductor layer 131 and a second contact hole 161 b for connecting the drain electrode 170 d with a drain region 131 d of the polycrystal semiconductor layer 131 are formed in the interlayer insulation layer 160 and the gate insulation layer 140. In addition, the source electrode 170 s and the drain electrode 170 d overlapping the polycrystal semiconductor layer 131 and separated from each other are disposed on the interlayer insulation layer 160, a planarization layer 180 is disposed on the source electrode 170 s and the drain electrode 170 d, and a pixel electrode 190 electrically connected to the drain electrode 170 d is disposed on the planarization layer 180.

Although an exemplary embodiment is illustratively shown in FIG. 2, the present invention may be applied to other forms of transistors and panels as well. For example, embodiments of the present invention may be applied to a thin film transistor array panel having a bottom gate structure in which the gate electrode is disposed below the semiconductor layer and the source and drain electrodes, in addition to a thin film transistor array panel having a top gate structure in which the gate electrode is disposed on the semiconductor layer as shown in FIG. 2, and various kinds of insulation layers and semiconductor layers, and various kinds of electrodes may be stacked in different sequences. For example, when the present invention is applied to the bottom gate structure, the buffer layer containing fluorine is disposed on the gate electrode, and the polycrystal semiconductor layer is disposed on the buffer layer. The buffer layer may be made of an insulation material, and may act as the gate insulation layer. As described above, the buffer layer in the present invention is made of an insulation material to act as various kinds of insulation layers. In other words, when the insulation layer is disposed below the semiconductor layer, the insulation layer may act as the buffer layer of embodiments of the present invention, while containing fluorine.

The thin film transistor array panel according to an exemplary embodiment of the present invention may be applied to displays such as an organic light emitting diode (OLED), a liquid crystal display (LCD), and the like.

FIG. 1 is a flow chart of a method of manufacturing the thin film transistor array panel according to an exemplary embodiment of the present invention. Hereinafter, a method of manufacturing the thin film transistor array panel will be described with reference to FIG. 1.

First, the buffer layer 120 a containing fluorine is stacked or formed on the insulation substrate 100 (S100), and the amorphous silicon layer 130 is stacked or formed on the buffer layer 120 a (S110). After the stacking is completed, a dehydrogenation process is performed on the buffer layer 120 a and the amorphous silicon layer 130 (S120). The dehydrogenation process is to decrease a content of hydrogen (H₂) in the buffer layer 120 a and the amorphous silicon layer 130, and may be performed by heat treatment at a high temperature (more than 450° C.). During the dehydrogenation process, hydrogen in the buffer layer 120 a is prevented from being diffused into the amorphous silicon layer 130 by the fluorine in buffer layer 120 a. After the dehydrogenation process is completed, the amorphous silicon layer 130 is crystallized into a polysilicon layer (S130). The crystallization process may be performed by, for example, laser annealing. Since laser annealing is performed at a low cost and has high efficiency, laser annealing is often preferred over other low temperature crystallization technologies. As one example, an excimer laser annealing (ELA) process using an excimer laser having a wavelength of 308 nm may be used for this laser annealing. Since the laser wavelength used in the excimer laser annealing has high absorptance in the amorphous silicon layer, the amorphous silicon layer is heated and melted in a short time, so as to manufacture the polysilicon layer without damaging the insulation substrate. The polycrystal semiconductor layer 131 is formed by patterning this polysilicon layer (S140). The patterning of the polysilicon layer may be performed by a microelectromechanical system (MEMS) based process such as a photolithography process, or the like. By patterning the polycrystal silicon layer, the polycrystal semiconductor layer 131 is formed, where the polycrystal semiconductor layer 131 includes the source region 131 s connected to the source electrode, the drain region 131 d connected to the drain electrode, and a channel region 131 c positioned between the source region 131 s and the drain region 131 d. Then, the gate insulation layer 140 is formed on the polycrystal semiconductor layer 131, a gate metal layer is formed on the gate insulation layer 140, and the gate metal layer is patterned to form a gate electrode 150 in an island shape on the channel region 131 c of the polycrystal semiconductor layer 131. The interlayer insulation layer 160 is formed on the gate electrode 150, and the first contact hole 161 a and the second contact hole 161 b, exposing portions of the source region 131 s and the drain region 131 d of the polycrystal semiconductor layer 131 respectively, are formed by patterning the interlayer insulation layer 160 and the gate insulation layer 140 together. Then, the source electrode 170 s and the drain electrode 170 d are formed to contact the source region 131 s and the drain region 131 d of the polycrystal semiconductor layer 131, respectively, through the first contact hole 161 a and the second contact hole 161 b. The planarization layer 180 is formed on the source electrode 170 s and the drain electrode 170 d, and the pixel electrode 190 is then formed on the planarization layer 180 to be connected to the drain electrode 170 d through a contact hole formed in the planarization layer 180 (S150).

Although an exemplary embodiment is illustratively shown in FIG. 1, embodiments of the present invention may be applied to methods of manufacturing thin film transistor array panels having bottom gate structures in which the gate electrode is disposed below the semiconductor layer and the source and drain electrodes, as well as methods of manufacturing thin film transistor array panels having top gate structures in which the gate electrode is disposed on the semiconductor layer as shown in FIG. 1. Embodiments of the invention also encompass various kinds of insulation layers and semiconductor layers, and various kinds of electrodes that may be stacked in different sequences. For example, when the method of the present invention is applied to the method of manufacturing the bottom gate structure, a process of stacking the buffer layer containing fluorine on the gate electrode is performed, and then, a process of stacking the amorphous silicon layer on the buffer layer is performed. The buffer layer may be made of an insulation material, and may act as the gate insulation layer. As described above, the buffer layer of embodiments of the present invention may be made of an insulation material to act as various kinds of insulation layers. In other words, when the insulation layer is disposed below the semiconductor layer, the insulation layer may act as the buffer layer of the present invention, while containing fluorine.

The method of manufacturing the thin film transistor array panel according to an exemplary embodiment of the present invention may be applied to manufacture of displays such as an organic light emitting diode (OLED), a liquid crystal display (LCD), and the like.

Hereinafter, the thin film transistor array panel and the method of manufacturing the same according to an exemplary embodiment of the present invention will be described with reference to FIGS. 3 to 9.

FIG. 4 schematically shows a thin film transistor array panel according to an exemplary embodiment of the present invention, and FIGS. 8 and 9 a to 9 c partially show modified exemplary embodiments according to different positions of a hydrogen diffusion prevention layer of the present invention.

First, referring to FIG. 4, a thin film transistor array panel according to an exemplary embodiment of the present invention may include the insulation substrate 100, the buffer layers 110 a and 110 b, the hydrogen diffusion prevention layer 120 b, the polycrystal semiconductor layer 131, the gate electrode 150, the source electrode 170 s, the drain electrode 170 d, and the pixel electrode 190.

Referring to FIG. 4, the buffer layer 110 a is disposed on the insulation substrate 100, and the hydrogen diffusion prevention layer 120 b is formed on the buffer layer 110 a. The hydrogen diffusion prevention layer 120 b contains fluorine. The buffer layer 110 b is disposed on the hydrogen diffusion prevention layer 120 b, and the polycrystal semiconductor layer 131 is disposed on the buffer layer 110 b. A gate insulation layer 140 is disposed on the polycrystal semiconductor layer 131, the gate electrode 150 overlaps the polycrystal semiconductor layer 131 and is disposed on the gate insulation layer 140, and an interlayer insulation layer 160 is disposed on the gate electrode 150. The first contact hole 161 a exposing the source region 131 s of the polycrystal semiconductor layer 131, and the second contact hole 161 b exposing the drain region 131 d of the polycrystal semiconductor layer 131, are formed in the interlayer insulation layer 160 and the gate insulation layer 140. In addition, the source electrode 170 s and the drain electrode 170 d, overlapping the polycrystal semiconductor layer and separated from each other, are disposed on the interlayer insulation layer 160. Also, the planarization layer 180 is disposed on the source electrode 170 s and the drain electrode 170 d, and the pixel electrode 190 is disposed on the planarization layer 180 to be electrically connected to the drain electrode 170 d.

Although an exemplary embodiment is illustratively shown in FIG. 4, the present invention may be applied to thin film transistor array panels having bottom gate structures as well as those having top gate structures as shown in FIG. 4. It may also be applied to structures having various kinds of insulation layers and semiconductor layers, and various kinds of electrodes stacked in different sequences. For example, when the present invention is applied to the bottom gate structure, the buffer layers with the hydrogen diffusion prevention layer interposed therebetween are disposed on the gate electrode, and the polycrystal semiconductor layer is disposed on the buffer layer. The buffer layer may be made of an insulation material, and may act as the gate insulation layer. As described above, the buffer layer in the present invention may be made of an insulation material to act as various kinds of insulation layers. In other words, when the insulation layer is disposed below the semiconductor layer, the insulation layer may act as the buffer layer of the present invention, by including a hydrogen diffusion prevention layer containing fluorine within.

The hydrogen diffusion prevention layer 120 b may be made of a material of the buffer layer along with fluorine. When the hydrogen diffusion prevention layer 120 b is constructed in this manner, the hydrogen diffusion prevention layer 120 b and the buffer layer may be continuously formed. The buffer layers 110 a and 110 b include a layer containing SiNx (hereinafter, referred to as a SiNx layer) and a layer containing SiOx (hereinafter, referred to as a SiOx layer) stacked on the SiNx layer. The hydrogen diffusion prevention layer 120 b may be deposited at, for example, the middle of the SiNx layer, an interface between the SiNx layer and the SiOx layer, the middle of the SiOx layer, and above the SiOx layer.

When specifically explaining the above structure with reference to FIGS. 8 and 9A to 9C, the buffer layers 110 a and 110 b and the hydrogen diffusion prevention layer 120 b may be stacked in the following order: buffer layer 110 a containing SiNx, the hydrogen diffusion prevention layer 120 b, the buffer layer 110 a containing SiNx, and the buffer layer 110 b containing SiOx as shown in FIG. 9A. The layers may also be stacked in the order: buffer layer 110 a containing SiNx, the hydrogen diffusion prevention layer 120 b, and buffer layer 110 b containing SiOx as shown in FIG. 8. Alternatively, the following order is also contemplated: buffer layer 110 a containing SiNx, buffer layer 110 b containing SiOx, the hydrogen diffusion prevention layer 120 b, and buffer layer 110 b containing SiOx as shown in FIG. 9B. In addition, although not shown in the drawings, the buffer layers and the hydrogen diffusion prevention layer may be stacked in the following sequence: buffer layer 110 a containing SiNx, buffer layer 110 b containing SiOx, and the hydrogen diffusion prevention layer 120 b. Alternatively, and as shown in FIG. 9c , the buffer layers and the hydrogen diffusion prevention layer may be stacked in the following sequence: buffer layer 110 a containing SiNx, the hydrogen diffusion prevention layer 120 b, buffer layer 110 a containing SiNx, buffer layer 110 b containing SiOx, the hydrogen diffusion prevention layer 120 b, and buffer layer 110 b containing SiOx. That is, one or more hydrogen diffusion prevention layers 120 b may be included. These layers 120 b may be stacked in any order with any other buffer layers.

Even though the stacked structures of the buffer layers 110 a and 110 b and the hydrogen diffusion prevention layer 120 b are described by preferable exemplary embodiments with reference to the drawings as described above, the invention is not limited to the drawings as shown and may include various stacked structures without departing from the spirit and scope of the appended claims. That is, any order of any such layers is contemplated.

The hydrogen diffusion prevention layer 120 b may be made of, for example, SiOF or SiNF in the exemplary embodiments.

FIG. 3 is a flow chart of a method of manufacturing a thin film transistor array panel according to an exemplary embodiment of the present invention, and FIGS. 5 to 8 sequentially show a method of manufacturing the polysilicon layer according to an exemplary embodiment of the present invention. Hereinafter, a method of preparing a thin film transistor array panel will be described with reference to FIGS. 3 and 5 to 8.

First, as shown in FIG. 5, the buffer layer 110 a is stacked on the insulation substrate 100 (S310), and as shown in FIG. 6, the hydrogen diffusion prevention layer 120 b containing fluorine is stacked on the buffer layer 110 a (S320). Then, as shown in FIG. 8, the buffer layer 110 b (S330) and the amorphous silicon layer 130 (S340) are sequentially stacked on the hydrogen diffusion prevention layer 120 b. After the stacking is completed, the dehydrogenation process is performed on the buffer layers 110 a and 110 b, the hydrogen diffusion prevention layer 120 b, and the amorphous silicon layer 130 as shown in the flow chart of FIG. 3 (S350). During the dehydrogenation process, hydrogen in the buffer layers 110 a and 110 b is prevented from being diffused into the amorphous silicon layer 130 due to fluorine in the hydrogen diffusion prevention layer 120 b. After the dehydrogenation process is completed, the amorphous silicon layer 130 is crystallized into a polysilicon layer (S360). The polycrystal semiconductor layer 131 is formed by patterning this polysilicon layer (S370). The polycrystal semiconductor layer 131 includes the source region 131 s connected to the source electrode, the drain region 131 d connected to the drain electrode, and the channel region 131 c positioned between the source region 131 s and the drain region 131 d. Then, the gate insulation layer 140 is formed on the polycrystal semiconductor layer 131, the gate metal layer is formed on the gate insulation layer 140, and the gate metal layer is patterned to form the gate electrode 150 in an island shape on the channel region 131 c of the polycrystal semiconductor layer 131. The interlayer insulation layer 160 is formed on the gate electrode 150, and the first contact hole 161 a and the second contact hole 161 b, exposing portions of the source region 131 s and the drain region 131 d of the polycrystal semiconductor layer 131 respectively, are formed by patterning the interlayer insulation layer 160 together with the gate insulation layer 140. Then, the source electrode 170 s and the drain electrode 170 d, separated from each other and contacting the source region 131 s and the drain region 131 d of the polycrystal semiconductor layer 131 respectively through the first contact hole 161 a and the second contact hole 161 b, are formed on the interlayer insulation layer 160. The planarization layer 180 is formed on the source electrode 170 s and the drain electrode 170 d, and the pixel electrode 190 is formed on the planarization layer 180 to be electrically connected to the drain electrode (S380).

Although an exemplary embodiment is illustratively shown in FIG. 3, the present invention may be applied to methods of manufacturing thin film transistor array panels having bottom gate structures in addition to those having top gate structures as shown in FIG. 3, and is applicable to various kinds of insulation layers and semiconductor layers, and various kinds of electrodes stacked in different sequences. For example, when methods of the present invention are applied to the manufacture of a bottom gate structure, a process of forming the buffer layers on the gate electrode is performed, wherein the process of forming the buffer layers includes a process of forming the hydrogen diffusion prevention layer between the buffer layers, and then, a process of stacking the amorphous silicon layer on the buffer layer is performed. The buffer layer may be made of an insulation material, and may act as the gate insulation layer. As described above, the buffer layer in embodiments of the present invention is made of an insulation material to act as various kinds of insulation layers. In other words, when the insulation layer is disposed below the semiconductor layer, the insulation layer may act as the buffer layer of the present invention, by forming the fluorine-containing hydrogen diffusion prevention layer within the insulation layer.

The hydrogen diffusion prevention layer 120 b may be made of a material of the buffer layer along with fluorine. When the hydrogen diffusion prevention layer 120 b is made in this manner, the hydrogen diffusion prevention layer 120 b and the buffer layer may be continuously formed to simplify the manufacturing process.

The hydrogen diffusion prevention layer 120 b may be formed on the buffer layer 110 a by plasma treatment using gas containing fluorine, as shown in FIG. 7.

The hydrogen diffusion prevention layer 120 b may be deposited at one or more process points including: in the middle of a process of stacking the SiNx layer, after a process of stacking the SiNx layer, in the middle of a process of stacking the SiOx, and after a process of stacking the SiOx layer.

When specifically explaining the above with reference to FIGS. 8 and 9 a to 9 c, the buffer layers 110 a and 110 b and the hydrogen diffusion prevention layer 120 b may be stacked in the order of buffer layer 110 a comprising SiNx, hydrogen diffusion prevention layer 120 b, buffer layer 110 a comprising SiNx, and buffer layer 110 b comprising SiOx as shown in FIG. 9a . Another order may be buffer layer 110 a including SiNx, hydrogen diffusion prevention layer 120 b, and buffer layer 110 b including SiOx as shown in FIG. 8. A further order may be buffer layer 110 a including SiNx, buffer layer 110 b including SiOx, hydrogen diffusion prevention layer 120 b, and buffer layer 110 b including SiOx as shown in FIG. 9 b.

In addition, the buffer layers and the hydrogen diffusion prevention layer may be stacked in the following sequence: buffer layer 110 a including SiNx, buffer layer 110 b including SiOx, and hydrogen diffusion prevention layer 120 b, as shown in FIG. 9c . Alternatively, the buffer layers and the hydrogen diffusion prevention layer may be stacked in the order of buffer layer 110 a including SiNx, hydrogen diffusion prevention layer 120 b, another buffer layer 110 a including SiNx, buffer layer 110 b including SiOx, hydrogen diffusion prevention layer 120 b, and buffer layer 110 b including SiOx. That is, one or more hydrogen diffusion prevention layers 120 b may be deposited in any order.

Even though the stacked sequences of the buffer layers 110 a and 110 b and the hydrogen diffusion prevention layer 120 b are described by preferable exemplary embodiments with reference to the drawings as described above, the invention is not limited to the drawings as shown and may include various stacked sequences without departing from the spirit and scope of the appended claims.

The hydrogen diffusion prevention layer 120 b may be deposited using, for example, SiOF or SiNF in the exemplary embodiments.

In addition, in the exemplary embodiments, the hydrogen diffusion prevention layer 120 b may be formed on the buffer layer 110 a by plasma treatment using gas containing fluorine, as shown in FIG. 7.

Hereinafter, effects obtained by exemplary embodiments of the present invention will be described with reference to FIGS. 10a and 10 b.

FIG. 10A schematically shows an effect obtained by an exemplary embodiment of the present invention, and FIG. 10B schematically shows an effect obtained by a Comparative Example of the present invention.

FIG. 10a schematically shows hydrogen diffusion generated during the dehydrogenation process after the insulation substrate 100, the buffer layer 110 a, and the hydrogen diffusion prevention layer 120 b, the buffer layer 110 b, and the amorphous silicon layer 130 are sequentially stacked. The purpose of the dehydrogenation process is to remove hydrogen from the buffer layers 110 a and 110 b and the amorphous silicon layer 130. When some hydrogen from the buffer layers 110 a and 110 b is trapped by the amorphous silicon layer 130, hydrogen trapped in the amorphous silicon layer 130 is diffused into the environment during subsequent processes such as a process of crystallizing the amorphous silicon layer 130 into the polysilicon layer, such that film burst may occur and surface roughness may be increased. However, when the hydrogen diffusion prevention layer 120 b is disposed between the buffer layers 110 a and 110 b, hydrogen escaping the buffer layers 110 a and 110 b is trapped in the hydrogen diffusion prevention layer 120 b. Since fluorine in the hydrogen diffusion prevention layer 120 b has an effect of preventing diffusion of hydrogen, the hydrogen diffusion prevention layer 120 b acts as a hydrogen trap site to maximize the dehydrogenation effect. When diffused hydrogen is trapped in the hydrogen diffusion prevention layer 120 b before arriving at the amorphous silicon layer 130, the amount of hydrogen trapped in the amorphous silicon layer 130 may be decreased so that problems such as film burst, an increase in roughness, and the like, may be decreased in the subsequent processes such as a crystallizing process, and due to a decrease in total amount of hydrogen in the buffer layers 110 a and 110 b, current flow may be improved, that is, characteristics of the LTPS thin film transistor may be improved.

FIG. 10b shows a Comparative Example. When the hydrogen diffusion prevention layer is not present in the buffer layers 110 a and 110 b, hydrogen in the buffer layers 110 a and 110 b are diffused and trapped in the amorphous silicon layer 130 in the dehydrogenation process, and therefore, the dehydrogenation effect is decreased. Then, hydrogen trapped in the amorphous silicon layer 130 escapes from the layer 130 during the process of crystallizing the amorphous silicon layer 130 into the polysilicon layer, such that film burst may occur and surface roughness may be increased.

FIGS. 11 and 12 are Tables showing experimental results according to an exemplary embodiment of the present invention.

FIG. 11 is Table showing experimental results which confirms a decrease in the hydrogen amount in the buffer layers when the hydrogen diffusion prevention layer 120 b containing SiNF is stacked between a buffer layer 110 a containing SiNx and a buffer layer 110 b containing SiOx. It is confirmed that in this case, the total amount (at %) of hydrogen in the buffer layers (110 a, 110 b) were decreased from 23.96 to 13.9, which corresponds to a decrease of 42%. In addition, it is confirmed that a Cu etchant etch rate (Å/s) was decreased from 47.8 to 6.6, such that etch damage was reduced, due to the fact that the hydrogen diffusion prevention layer 120 b exhibits tight chemical binding, such that hardness of the buffer layers 110 a is increased. When hardness of the buffer layers 110 a is increased, diffusion of hydrogen generated from a lower part may be more effectively chemically and physically prevented.

FIG. 12 is Table showing experimental results which confirms a decrease in the hydrogen amount in the buffer layers when a hydrogen diffusion prevention layer 120 b including SiOF is stacked between a buffer layer 110 a including SiNx and a buffer layer 110 b including SiOx. It is confirmed that the total amount (at %) hydrogen in buffer layers (110 a, 110 b) were decreased from 6.01 to 3.69, which corresponds to a decrease of 39%. In addition, it is confirmed that in measurement of FT-IR, a Si—O peak position (1/cm) was increased from 1056.5 to 1067.0, which means that SiOF is stronger than SiOx in view of Si—O bond. When the hydrogen diffusion prevention layer 120 b consisting of SiOF having strong Si—O bond is stacked, the hardness of the buffer layer 110 a is increased, and diffusion of hydrogen generated from a lower part may be more effectively chemically and physically prevented.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Furthermore, different features of the various embodiments, disclosed or otherwise understood, can be mixed and matched in any manner to produce further embodiments within the scope of the invention.

<Description of Symbols>

100: insulation substrate 110 a, 110 b: buffer layer

120 a: buffer layer containing fluorine 120 b: hydrogen diffusion prevention layer

130: amorphous silicon layer 131: polycrystal semiconductor layer

140: gate insulation layer 150: gate electrode

160: interlayer insulation layer 170 s: source electrode 170 d: drain electrode

180: planarization layer 190: pixel electrode 

What is claimed is:
 1. A thin film transistor array panel comprising: an insulating substrate; a polycrystal semiconductor layer formed on the insulating substrate; a buffer layer formed below the polycrystal semiconductor layer containing fluorine; a gate electrode overlapping the polycrystal semiconductor layer; a source electrode and a drain electrode overlapping the polycrystal semiconductor layer and separated from each other; and a pixel electrode electrically connected to the drain electrode, wherein the buffer layer comprises a first buffer layer, a second buffer layer, and a hydrogen diffusion prevention layer disposed between the first buffer layer and the second buffer layer.
 2. The thin film transistor array panel of claim 1, wherein: the hydrogen diffusion prevention layer includes the fluorine.
 3. The thin film transistor array panel of claim 2, wherein: the diffusion prevention layer comprises a material of the first buffer layer or the second buffer layer, and the fluorine.
 4. The thin film transistor array panel of claim 2, wherein: the first buffer layer includes a SiNx layer and the second buffer layer includes a SiOx layer, and the hydrogen diffusion prevention layer is disposed at one or more of a middle of the SiNx layer, an interface between the SiNx layer and the SiOx layer, a middle of the SiOx layer, and above the SiOx layer.
 5. The thin film transistor array panel of claim 4, wherein: the hydrogen diffusion prevention layer comprises SiOF or SiNF. 